Young Couple's Ford F-150 Kept Having Problems Even After an Engine Replacement. Then, a Mechanic Found the Real Problem

Replacing an engine is one of the most expensive repairs a vehicle owner can face. We can't even imagine the frustration someone would feel when discovering that the replacement hasn't solved the problem, especially when they depend on that vehicle every day.

That's the situation a young Utah couple, Logan and Delaney, found themselves in after buying a used 2018 Ford F-150. What was supposed to be a dependable truck became a months-long ordeal involving repeated workshop visits and an engine replacement.

The truck suffered from misfires, low oil pressure warnings, and concerns about engine compression. Even after another shop installed a used replacement engine, the problems kept returning, leaving the couple without reliable transportation.

Their story eventually reached Dave's Auto Center through its Can Dave Fix It? YouTube series. Rather than assume the replacement engine was defective, Dave and his longtime technician Tyson decided to investigate what was actually happening.

A Replacement Engine Didn't End the Trouble

The F-150 had approximately 148,000 miles and a 5.0-liter Coyote V8. According to the owners, its original engine had shown low compression in two cylinders, prompting the costly replacement.

Yet the check-engine light returned shortly afterward, and the couple later added five quarts of oil after believing the engine was nearly empty. Dave discovered the crankcase was actually several quarts overfilled, partly because clean oil was difficult to see on the dipstick.

The Real Problem Was in the Exhaust

After correcting the oil level and checking the cooling system for leaks, the team found no active misfires. The persistent fault was a P0420 code indicating poor catalytic-converter efficiency on one engine bank.

Further testing showed abnormal downstream oxygen-sensor readings, while temperature checks suggested the converters weren't working properly. Once removed, one converter was visibly breaking apart internally, confirming serious exhaust-system damage.

Dave suspected earlier misfires had contaminated the converters, although he couldn't establish exactly when the damage occurred. Both converters were replaced, and the team corrected loose brackets and improper hardware left from previous work.

A Proper Diagnosis Makes the Difference

The repairs weren't considered finished simply because the warning light disappeared. Tyson drove the truck for approximately 150 miles, checking that the emissions monitors completed their tests without returning fault codes.

Dave also explained his four-step diagnostic approach: condition, cause, correction, and confirmation. It's a straightforward process, but one that can prevent expensive parts replacements from becoming exercises in guesswork.

A Much-Needed Break for the Couple

Dave offered to replace both catalytic converters free of charge, leaving Logan and Delaney pleasantly surprised. He simply asked them to pay the kindness forward whenever they had the opportunity.

When the couple returned to collect their F-150, they thanked Dave and Tyson for their help, saying the long drive to the workshop had been worth it. Dave also became visibly emotional while praising Tyson, his trusted technician of 31 years, admitting that he didn't tell him often enough how much he appreciated him.

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